1. Field of the Invention:
This invention relates to an oil pressure type impulse torque generator for a torque wrench and the like, which is entirely free from "burning phenomenon" at the seal surfaces of a main shaft and a liner.
2. Description of the Prior Art:
Torque wrenches which are pneumatic tools used in bolt tightening operations and the like generate impact by a mechanical method based on the turning power of a rotor and such impact is converted into the desired torque. As the impact torque obtained by this mechanical method involves high impact noise, it can cause noise pollution. Also, there is a risk of operators being affected by Steinbrocken syndrome or Raynaud's phenomenon due to vibration caused by impact. With this in view, torque wrenches which use oil pressure for obtaining impact torque to prevent noises and vibration have been developed. Such torque wrenches have an oil pressure type torque generator with one blade or a plurality of blades at a main shaft (four blades in the case of Japanese Patent Application Publication Gazette No. 41-5800). In the case of the former or the single blade construction, oil pressure in a rotatable liner through which a main shaft is put, namely, oil pressure of the impact torque generator becomes higher, for which a more precise and stronger sealing construction is required. In the case of the latter or the construction using plural blades, an impact is generated at least twice in each revolution of the liner.